Cathode ray tube



Patented May 21, 1946 UNITED aaasii CATHODE RAY TUBE John Mathieson Dodd Walter Miller,

s, Eimperley, Sale, England,

and Charles assignors to Metropolitan-Vickers Electrical Company Limited, London, England, a company of Great Britain Application September 21, 1943, Serial No. 503,276 In Great Britain August 8, 1941 a 3 Claims.

This invention relates to magnetic apparatus for providing time bases for cathode ray tubes.

According to the invention this apparatus comprises two or more magnetic arms preferably of two pairs of axially disposed permanent bar magnets or electromagnets with like poles against the middle laminated disc which extends on the opposite side of the axis to the other two laminated discs. With this form a substantially straight line law time base can be achieved. Alternatively, the permanent magnet or electromagnet may itself be stationary and located with small clearance from the rotating members. Or the permanent or bar magnet or magnets may be fixed elsewhere in the magnetic circuit. By theaddition of encoils, numerous forms of time base can be duced,

The time base apparatus above set forth may be conveniently used in a panoramic radio receiver such as described in Electronics June 1940, and wherein the scanning of a specified waveband is effected by rotation of a set of tuning means and the condensers, and clutch may be linked with the switch for the motor supply, so as to be automatically declutched when the switch is moved to the open position.

Thus, the invention is in general notably applicable for the deflection of a cathode ray beam either recurrently or to a controllable position, at will, and wherein the displacement of the beam in one direction or axis indicates a relation or a plurality of relations simultaneously, between phenomena causing displacement of the beam angles, such relation being either continuously observable by automatic recurrent control or examinable in detail by manual control. The invention, according to this aspect thereof, includes within its scope the modipreferably this On the magnetic conveniently provides a tuning indicator and frequency meter such as for a panoramic receiver or for examining impedance-frequency characteristics of radio receiver or of any tuned circuits. The invention is especially, but not exclusively, of use in the single span type of radio receiver forming the subject of U. S. application Serial No. 514,478, filed December 16, 1943, and then may be applied to the second of the frequency changers.

Provision may be made for extinguishing or trapping the cathode ray beam during its return sweep, and for reducing the brilliance of the spot during manual scanning, in accordance with U. S. application Serial No. 503,282, filed September 21, 1943.

Where the reluctance varying means is oscillatory or vibratory it may be for example the armature of an electric be driven by such a device.

In the accompanying drawing:

Figure 1 is a showing by way of example a magnetic system base for a cathode ray tube,

Figure 2 is an underneath section of the arrangement shown in Figure 1, and

Figure 3 is a diagrammatic view of a clutch device whereby the automatic operation may be changed to manual operation, as hereinbefcre set forth.

buzzer or the like, or

the purposes hereinbefore stated. The members I, 2 with the pole pieces 3, 4 provide the magnetic circuit and associated with these members are means adapted to cause a variable reversing flux to traverse the neck 5 of the cathode ray tube to produce a predetermined deflection movement of the cathode ray beam.

According to the simple arrangement illustrated, the means for thus variably and reversibly magnetising the pole pieces 3 and 4 through the arms I and 2 respectively comprises a permanent magnet system with laminated poles mounted on a rotating shaft '8 carried in bearings in fixed members 9 and It. Fixed to the shaft 8 are three soft iron laminated pole members of disc form, namely the upper and lower members H and [2 which are eccentrically disposed in'similar position and the intermediate member I3 of similar shape but twice the axial thickness of the member H or l2 and oppositely eccentrically disposed on the shaft 8 with respect to the members i l and I2, as will be clearly seen from Figure 2. The shaft 8 material. The laminated pole pieces ll, 12 and i3 are spaced apart as shown by at least four permanent bar magnets, namely M and I5 be tween the pole pieces H and i3, and magnets'lfi and I1 between the pole pieces l2 and I3. The magnets are arranged so as to have like polarity adjacent the pole pieces II and l2 and like but opposite polarity adjacent the pole piece 13, as indicated by N, S.

The shaft 8 may be rotated by any suitable means normally continuously, for example by a clockwork or electric motor l8 (Fig. 3) such as through the manually controllable clutch device 19.

It will be appreciated that when the members H, I2 and I3 are of disc shape as shown more especially in Fig. 2, the resultant deflection of the cathode ray beam can be made to correspond with the rotation of the shaft 8, thus producing a pyramid wave form, giving a straight line time base.

is of non-magnetic I ally to cause the bevel The rotating magnet system H to H is substantially astatic, but it will be appreciated that one set such as [2, l6 and 11 may be omitted, with the member 13 made the same axial thickness as the member ll.

It is repeated that the numerous modifications mentioned in the preamble hereof may be made within the scope of the appended claims.

Referring now more particularly to Fig. 3 of the drawing, it may be assumed that the lower end of the shaft 8 is of square section, and sliding upon'it is a bevel wheel 20 fixed to the sleeve 2| having a grooved collar 22 which is movable up and down by a lever 23 which it may be assumed is pivoted at 24 and operable manuwheel 20 either to engage with'the bevel pinion 25 rotatable by the manual member '26 or to cause a depending peg 21 or other dog clutch member to engage with a counterpart clutch member 28 fixed to the shaft of the motor [8.

We claim:

1. Magnetic deflection apparatus ior'providing time bases for cathode ray tubes, comprising arms constituting'p'art of a magnetic circuit and normally in fixed relationship with the tube, low reluctance poles carried by said armsjadjacent the neck of the cathode 1 ray tube and adapted directly and magnetically to deflect the beam, and a rotatable magnetic device located remotely from the tube in the flux path through said arms and in such a position that when rotated at constant speed the flux in said circuit, and hence the deflection of the'beam,'may be varied according to-a predetermined law.

2. Magnetic deflection apparatus for providing time bases for cathode ray tubes, comprising at least two magnetic arms which at one end have low reluctance poles adjacent the neck of the tube adapted directly and magnetically to deflect the beam, means for magnetizing said poles through said arms, and a rotatable permanent magnet system rotatably mounted within said arms and adapted when rotated to vary the magnetic flux in said poles and hence the deflection of the beam according to a predetermined law.

3. Apparatus as defined in'claim 2, wherein said permanent magnet'system comprises substantially astaticallyarranged permanent magnets.

JOi-IN MATHIESON DODDS. CHARLES VJAL'IE'R MILLER. 

